OTL amp owners

[BruceD]

Ah wonderful nostalgia-indeed lovely musical Speakers the Beveridge--I remember visiting the Santa Barbara HQ and being warmly welcomed by the

Charming Mr. Harold B!--I was even privy to a sneak peak at the 2W's(?) finished in Mirrorball Panels for Julie Andrews !

Good to hear the brand are still with us

Good Luck

BruceD

 

[c1ferrari]

Hi there,

That's exciting, I understand that Rick Beveridge is again restoring panels. Modjeski said that he might take a crack at it if he could get settled in his new home and found the time. My panels are, knock on wood, fine.

My Model 3's are now running direct drive and sub frequencies crossed over with a first order cap to stereo subs. I would jump on some Model 2's if I could find them. The Direct drive on the 3's make quite a difference.

http://rickbeveridge.com


Thanks.

Rick worked on my Model 3's and 2's. Roger completed work on my amps when he resided in Santa Barbara.
I hope to have the Model 2 fully restored.

 

[morricab]

I had the Silvaweld OTL Reference monoblocks. The sound was thrilling but the heat unbearable...

 

[Ron Resnick]

http://www.theaudiobeat.com/equipment/atma_sphere_ma2_mk31.htm

I wrote about the incredible crystalline transparency and clarity I heard from the Einstein Silver Bullet OTL Mk. II amplifiers, yet I found the presentation "lean" and lacking the richness and full-bodiedness I am used to with (transformer coupled) tube amps.

Marc describes this same phenomenon comparing Atma-Sphere amps to Lamm hybrids:

[Lamm] adds up to a sense of musical rightness, a quality that the Atma-Sphere amps also possess, even if they achieve it in different ways -- with their standard-setting transparency. This makes for a kind of realism that the Lamm amps don't quite achieve, one that's about revealing the unique qualities of each recording. The midrange of the Atma-Sphere amps is so light-filled and vivid that it seems improbable to be coming from anything other than live music. In contrast, the mids of the M1.2s are more consistent with those of very good tubes -- full-bodied and rounded, a touch dark in tonal terms.​

Now that I have heard the crystalline transparency of OTL I kind of feel like there is no going back to conventional tube amps. And yet . . . there was that leanness I am not sure I can get used to (even if it is more "accurate" than the slightly "gauzy" sonic layer of the output transformer).

 

[bonzo75]

Most OTLs won't be able to drive the speakers that lamm hybrids are being used for

 

[Ron Resnick]

I agree with that. But I was focusing on the midrange transparency of OTL versus the midrange richness of transformer output tube amps.

 

[morricab]

I agree with that. But I was focusing on the midrange transparency of OTL versus the midrange richness of transformer output tube amps.

That leanness, which my Silvaweld OTLs also had to a small degree, is partially due to them being Class AB with negative feedback. The bigger Atmaspheres go without feedback but are not Class A. By most accounts the Joule Electras were richer sounding, particularly when run sans feedback.

A single ended OTL to me might be the holy grail. I know two mfg. of such devices. Transcendent sound (kit) and Aries Cerat. I think AC monos are 100 watts...something to think about...

 

[Ron Resnick]

Legislative history shows that many people found the Joule Electras to be richer sounding (Ralph disagrees with this). But what is the reason in the design that people found the Joule Electras richer sounding?

I think the MA-2 is pure Class A.

Do you mean that Aries Cerat Collatio II mono (80 watts)?

Have you heard Ralph's Novacron amp? (It uses the same output tube as the Joule Electras, I believe.)

 

[awsmone]

having had the atmaspheres, crystalline clarity is spot on, they are Class A, circlotron circuits with multiple tube don't need much feedback as are inherently stable

futterman or totem pole otl need feedback to stabilise circuit

i have only heard two 6c33 otl and this was a lusher sound, both had 6sn7 drivers

with a circlotron otl the bandwidth and slew rate are both pretty amazing.....no going back

 

[bonzo75]

Did you hear any on stats, Andrew?

 

[BruceD]

Did you hear any on stats, Andrew?

I've heard them on David Magnan's Stacked Quads in Camarillo CA

Sorry Andrew--your call:b

BruceD

 

[bonzo75]

I've heard them on David Magnan's Stacked Quads in Camarillo CA

Sorry Andrew--your call:b

BruceD

How was that. Did it play orchestral well?

 

[BruceD]

How was that. Did it play orchestral well?

Yes Ked, I will admit it was a few years back --I presume the Amps have progressed somewhat since then.

I do recall David played only Classical Vinyl--but knowing --as I'm sure you are aware of the limitations of the Quads--even a stacked pair

cannot do full orchestral climaxes to their sonic extremes. I have photo of the setup which I shall endeavour to find and Post here.

I cannot recall the Cartridge --it may have been the Win Strain Gauge.

BruceD

 

[awsmone]

Sorry only on cones and horns Ked

 

[bonzo75]

Do you have a pic of the horns? Was it like a voice of theatre design?

 

[microstrip]

Legislative history shows that many people found the Joule Electras to be richer sounding (Ralph disagrees with this). But what is the reason in the design that people found the Joule Electras richer sounding?

I think the MA-2 is pure Class A.

Do you mean that Aries Cerat Collatio II mono (80 watts)?

Have you heard Ralph's Novacron amp? (It uses the same output tube as the Joule Electras, I believe.)

Although not fully class A - no true tube OTL of significant power can be class A when using your speakers - the MA-2 is biased at 1.2A - much more than common class A/B tube or SS amplifier. It is what was called a very enriched class A/B amplifier, most of time working in class A.

Why going for an expensive and hard to get tube (the 6C33) when you can use the well sounding, cheap, reliable and safe 6AS7?

 

[Aries Cerat]

Although not fully class A - no true tube OTL of significant power can be class A when using your speakers - the MA-2 is biased at 1.2A - much more than common class A/B tube or SS amplifier. It is what was called a very enriched class A/B amplifier, most of time working in class A.

Why going for an expensive and hard to get tube (the 6C33) when you can use the well sounding, cheap, reliable and safe 6AS7?

Very true.Even for many SS amplifier who claim "Class A" ,all it takes is a look at their idle current to take the claim of Class A away.

That is why we biased our SS Class A amp at 12A and the
SE OTL at 5.2A idle,but that is another story though In a world with green technology frenzy,such exercises in design are asking for trouble from our friend Al Gore and likes

 

[Ron Resnick]

having had the atmaspheres, crystalline clarity is spot on, they are Class A, circlotron circuits with multiple tube don't need much feedback as are inherently stable

futterman or totem pole otl need feedback to stabilise circuit

i have only heard two 6c33 otl and this was a lusher sound, both had 6sn7 drivers

with a circlotron otl the bandwidth and slew rate are both pretty amazing.....no going back

Does Ralph's Novacron display a lusher sound than his M-60 or MA-1?

 

[Ron Resnick]

I see that the Tenor 75 OTL used 6C33C tubes!

I think I rest my case (Joule Electra and Tenor) that for some reason the 6C33C OTL amps sound less lean than the 6AS7 OTL amps.

 

[morricab]

Legislative history shows that many people found the Joule Electras to be richer sounding (Ralph disagrees with this). But what is the reason in the design that people found the Joule Electras richer sounding?

I think the MA-2 is pure Class A.

Do you mean that Aries Cerat Collatio II mono (80 watts)?

Have you heard Ralph's Novacron amp? (It uses the same output tube as the Joule Electras, I believe.)

No push/pull OTL is pure Class A. It seems though that the Joule Electras were richly biased and had adjustable feedback (from zero to ?).

Yes, I meant the Collatio IIs. They are Single Ended OTLs and therefore HAVE to be Class A.

I found the Atmaspheres I heard to be somewhat leanish like my Silvaweld OTL and others I have heard (like Graaf GM70 and GM200, Transcendent Sound Beast, Tenor OTL, Einstein OTL etc.). Mine were with the 6C33C tube as were the Einsteins, Tenor and the Graaf, so that tube doesn't have to sound rich at all. I haven't heard the Joules but most reports were that they were rich sounding.